Bicycle front fork assembly

ABSTRACT

A wheel support portion for a bicycle, such as a front fork assembly, arranged to reduce vibrations that originate at the bicycle wheel and are transmitted to the rider of the bicycle through the wheel support. Desirably, the front fork assembly is configured to be supported by a bicycle frame and includes a pair of fork legs, which extend in a downward direction along opposing sides of a front wheel of the bicycle. Preferably, the fork legs are configured to support the front wheel at their lower ends. Each of the fork legs defines a cavity and a damping member is positioned within the cavity. Also disclosed is a preferred method of manufacturing the wheel support.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/417,996, filed May 3, 2006, scheduled to issue as U.S. Pat. No.7,175,191, which is a continuation of U.S. patent application Ser. No.10/692,226, filed Oct. 23, 2003, now U.S. Pat. No. 7,144,028, which is acontinuation of U.S. patent application Ser. No. 10/195,830, filed Jul.12, 2002, now U.S. Pat. No. 6,669,218.

INCORPORATION BY REFERENCE

The entireties of U.S. patent application Ser. No. 11/417,996, filed May3, 2006, U.S. patent application Ser. No. 10/692,226, filed Oct. 23,2003, and U.S. patent application Ser. No. 10/195,830, filed Jul. 12,2002, are hereby expressly incorporated by reference herein and made apart of the present disclosure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to bicycles. More particularly,the present invention relates to a bicycle front fork configured toreduce vibrations transmitted to a rider of the bicycle.

2. Description of the Related Art

Bicycle riding and racing often takes place on less than ideal terrainconditions. For example, bicycle touring and racing may often take placeon country roads, which may be unpaved or where the pavement may berough and irregular, even when new. In more populated areas, asignificant portion of paved roads may be damaged and in need of repair.When traversed by the bicycle, these irregular surfaces transmitvibrations to the bicycle. Furthermore, the surface of even relativelynew pavement, while acceptable for motor vehicles, may be rough enoughto transmit significant vibration to a bicycle. Accordingly, mostbicyclists spend at least a significant portion of their riding timetraversing rough or irregular surfaces. Vibrations induced by suchterrain, if not sufficiently dampened, may be transmitted to the riderof the bicycle. When transmitted to the rider, these vibrations oftencause discomfort and fatigue.

Several methods for damping terrain-induced vibrations have beenutilized. For example, the bicycle may be equipped with front and/orrear suspension assemblies, which permit the suspended wheel to moveagainst a biasing force relative to the bicycle frame. Although highlyfavored in some applications, such as bicycles intended primarily foroff-road use, such suspension assemblies have generally beenunsuccessful in connection with bicycles primarily intended for use onpaved surfaces (i.e., road bicycles), where low weight and aerodynamicsare considered highly important. Furthermore, such suspension assembliesare intended to absorb large bumps and may not be effective at isolatingvibrations due to inherent friction within the assembly, which mayprevent movement of the suspension assembly in response to small forces.

In road bicycle applications, it has recently become popular to utilizematerials having improved damping properties in comparison to metals toform a portion of the bicycle between the wheels and the rider. Forexample, a composite material of carbon fiber fabric within a resinmatrix (“carbon fiber”) is often used in an attempt to isolateroad-induced vibrations from the rider of the bicycle. In someinstances, the entire frame of the bicycle may be comprised of a carbonfiber material. However, due to the high manufacturing costs associatedwith molding carbon fiber, such bicycle frames are expensive tomanufacture. Another common method is to produce the main frame of amore conventional material, such as steel, aluminum or titanium, andprovide smaller component parts of carbon fiber material in an attemptto reduce vibration. For example, the front fork, seat post, handlebars,and stay portions of the frame (i.e., seat stays and/or chain stays) maybe produced from a carbon fiber material.

Such an arrangement has been more successful in isolatingterrain-induced vibrations from reaching the rider of the bicycle incomparison with bicycle frames and components comprised entirely ofmetal. However, although carbon fiber is lightweight and exhibitsimproved vibration damping characteristics in comparison to metal, asignificant amount of vibration may nonetheless be transferred throughcomponents made from carbon fiber.

One proposed solution to carbon fibers undesirable transmission ofvibrations is to incorporate an additional material into the carbonfiber fabric that is used to make the final carbon fiber product. Forexample, a weave of titanium filaments has been incorporated into carbonfiber fabric in an attempt to reduce the amount of vibration that istransmitted through components made of carbon fiber. However, such asolution necessitates a complex manufacturing process and, thus,increases the cost of the final product.

SUMMARY OF THE INVENTION

Accordingly, a need exists for a cost-effective method of reducingvibrations from being transmitted from the wheels of a bicycle to therider of the bicycle. Preferred embodiments of the front fork assemblyare constructed from a carbon fiber material and includes a cut-outportion on each leg of the fork assembly, which defines a cavity forreceiving a separate vibration damping member. Preferably, the vibrationdamping member is constructed from an elastomeric material and isretained with a friction fit within the cavity of each leg of the frontfork.

A preferred embodiment is a bicycle front fork assembly including asteer tube and a pair of fork legs extending in a downward directionfrom the steer tube and spaced from one another in a lateral direction.Each of the pair of legs has an upper portion, an intermediate portionand a lower portion and defines a substantially fixed length. The forkassembly is configured to support a wheel at the lower portions of thepair of legs and the pair of legs are interconnected at the upperportion. Each of the intermediate portions has an internal wall definingan internal cavity. A damping member is positioned within the cavity andcontacts the internal wall. The damping member comprises a vibrationdamping material.

A preferred embodiment is a bicycle front fork assembly including asteer tube and a pair of hollow, tubular legs extending in a downwarddirection from the steer tube and spaced from one another in a lateraldirection. Each of the pair of legs defines a substantially fixedlength. The fork assembly is configured to support a wheel at a lowerend of the pair of legs. Each of the pair of legs has an outer wallportion and an internal wall portion. The internal wall portion extendsfrom a first side of the outer wall portion to a second side of theouter wall portion opposite the first side. The internal wall portiondefines an internal cavity. A damping member positioned within thecavity and contacts the internal wall. The damping member comprising avibration damping material.

A preferred embodiment is a bicycle including a frame, which supports apedal crank assembly and a rear wheel. The pedal crank assembly isconfigured to drive the rear wheel. A front fork assembly is rotatablysupported by the frame for pivotal movement about a steering axis. Thefork assembly is configured to support a front wheel of the bicycle at alower end of the fork. The fork assembly includes a steer tube and apair of hollow, tubular legs. The pair of legs extend in a downwarddirection from the steer tube and are spaced from one another in alateral direction and define a substantially fixed length. Each of thepair of legs has an outer wall portion and an internal wall portion. Theinternal wall portion extends from a first side of the outer wallportion to a second side of the outer wall portion opposite the firstside. The internal wall portion defines an internal cavity. A dampingmember is positioned within the cavity and contacts the internal wall.The damping member comprises a vibration damping material.

A preferred embodiment is a bicycle including a main frame portion. Afront wheel and a rear wheel are connected to the main frame portion. Apedal crank assembly supported by the main frame and being configured todrive the rear wheel. A wheel support portion is connected to the mainframe at a first end and supports one of the front wheel and the rearwheel at a second end. The wheel support portion includes a pair ofhollow, tubular legs extending along opposing sides of the one of thefront wheel and the rear wheel. Each of the pair of legs has an outerwall portion and an internal wall portion and defines a substantiallyfixed length. The internal wall portion extends from a first side of theouter wall portion to a second side of the outer wall portion oppositethe first side. The internal wall portion defines an internal cavity. Adamping member is positioned within the cavity and contacts the internalwall. The damping member comprises a vibration damping material.

A preferred embodiment involves a wheel support for a bicycle includinga body having a pair of legs. Each of the legs has a first end, a secondend, and an intermediate portion extending between the first and secondends. The pair of legs are interconnected at the first ends andconfigured to support a bicycle wheel at the second ends. Each of thepair of legs define a substantially fixed length between the first andsecond ends. Each of the intermediate portions include an outer wallportion and an internal wall portion, which defines a cavity. A dampingmember is positioned within the cavity and contacts the internal wall.The damping member comprises a vibration damping material. The outerwall portion and the damping member each define a portion of an externalsurface of the wheel support.

A preferred embodiment involves a wheel support for a bicycle includinga body having a first leg and a second leg each having a first end, asecond end, and an intermediate portion extending between the first andsecond ends. The first and second legs are interconnected at the firstends and configured to support a bicycle wheel at the second ends. Eachof the first and second legs define a substantially fixed length betweenthe first and second ends. Each of the intermediate portions include anouter wall portion and an internal wall portion, which defines a cavity.A damping member is positioned within the cavity and contacts theinternal wall. The damping member comprises a vibration dampingmaterial. Each of the cavities extend a distance along the fixed lengthof the first and second legs that is less than the fixed length.

A preferred embodiment involves a method of manufacturing a wheelsupport for a bicycle. The method includes constructing a body includinga pair of legs interconnected at a first end and configured to support abicycle wheel at a second end. Each of the pair of legs define asubstantially fixed length between the first end and the second end. Anintermediate portion extends between the first and second end andincludes an outer wall portion and an internal wall portion, whichdefines a cavity. The method also includes inserting a damping memberinto the cavity, the damping member comprising a vibration dampingmaterial.

A preferred embodiment is a bicycle including a main frame portion, awheel, and a substantially rigid wheel support. The wheel support iscoupled to the main frame portion at a first end and supports the wheelat a second end. An outer wall of the wheel support defines an openingto a cavity. A damping member is positioned within the cavity anddampens vibrations introduced to the wheel support by the wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention are described with reference to drawings of a preferredembodiment, which is intended to illustrate, and not to limit, thepresent invention. The drawings comprise six figures.

FIG. 1 is a side elevational view of a bicycle incorporating a preferredfront fork assembly.

FIG. 2 is a top, left side, and rear perspective view of the front forkassembly of FIG. 1.

FIG. 3 is a front view of a portion of the bicycle and front forkassembly of FIG. 1.

FIG. 4 is a cross-section view of the left leg portion of the front forkassembly of FIG. 1 taken along line 4-4 of FIG. 2.

FIG. 5 is a partial cross-section of the left leg of the front forkassembly of FIG. 1 taken along line 5-5 of FIG. 4.

FIG. 6 is a partial sectional view of the left leg of the front forkassembly of FIG. 1 taken along line 6-6 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a bicycle, which is referred to generally by thereference numeral 10. The bicycle 10 includes a frame 12, whichrotatably supports a wheel support, or front fork assembly 14, near aforward end of the frame 12 for rotation about a steering axis. A lowerend of the fork assembly 14 supports a front wheel 16 of the bicycle 10.A handlebar assembly 18 is connected to an upper end of the fork 14 forrotating the fork assembly 14 and front wheel 16 about the steering axisof the bicycle 10. In addition, the handlebar assembly 18 may includeone or more rider controls, such as shifting or braking controls.

A rear wheel 20 of the bicycle 10 is supported near a rearward end ofthe frame 12. A pedal crank assembly 22 is rotatably supported by alower portion of the frame 12. A drive chain 24 extends between thepedal crank assembly and the rear wheel to transfer power therebetween,as is well known in the art.

A front brake caliper 26 is supported by the front fork assembly 14 andis configured to selectively apply a squeezing force to a rim of thefront wheel 16. Similarly, a rear brake caliper 28 is supported by theframe 12 and configured to selectively apply a squeezing force to a rimportion of the rear wheel 20. Alternatively, other types of brakingsystems may also be used.

A seat post 30 extends in an upward direction from the frame 12 andsupports a seat 32 on its upper end. The seat post 30 may be adjusted inheight relative to the frame 12 to adjust a seat height of the bicycle10.

Preferably, the frame 12 includes a main frame portion 34 and a wheelsupport, or rear frame portion 36. The rear frame portion 36 desirablyincludes a pair of lower legs, or chain stay members 38 (only oneshown), extending on each side of the rear wheel 20 from a lower portionof the main frame 34. In addition, the rear frame portion 36 includes apair of upper legs, or seat stay members 40, extending from an upperportion of the main frame 34 on each side of the rear wheel 20 and beingconnected to a rear end of the chain stays 38 near a hub axis of therear wheel 20.

Desirably, at least the main frame 34 is constructed from a plurality oftubular, metal pieces welded together. For example, the main frame 34may be constructed from aluminum, steel or titanium tubing.Alternatively, the frame may comprise a composite material and may beconstructed as a unitary piece. In addition, other suitable materialsand/or construction methods may also be used, as will be appreciated byone of skill in the art.

As described above, the front fork assembly 14 preferably is constructedto reduce the amount of vibration passed from the front wheel 16 to thehandlebar assembly 18, and thus the rider of the bicycle 10.Additionally, other components of the bicycle 10 may also be constructedto reduce vibration transfer. For example, the seat post 30 may beconstructed to include a damping member 60 a (FIG. 1) in a mannersimilar to the present fork assembly 14 to reduce the transmission ofvibrations from the frame 12 to the seat 32 and, thus, the rider of thebicycle 10. Such a seat post 30 is described in greater detail in anapplication assigned to the assignee of the present application andentitled BICYCLE SEAT POST ASSEMBLY (U.S. patent application Ser. No.10/195,831, filed Jul. 12, 2002, Publication No. US 2004/0084872 A1),which is hereby incorporated by reference in its entirety and made apart of this application. Furthermore, other components and/or portionsof the bicycle 10, such as the chain stays 38 or seat stays 40 of theframe 12, may be similarly arranged to include a damping member 60 b, 60c, respectively, to reduce the transmission of vibrations from thewheels 16, 20 to the rider of the bicycle 10, as will be appreciated byone of skill in the art in light of the teachings of the presentapplication.

With reference to FIGS. 2 and 3, a preferred front fork 14 isillustrated in greater detail. In FIG. 2, the front wheel 16 has beenomitted and in FIG. 3, the front wheel 16 is shown in phantom for thepurpose of clarity. As is described in greater detail below, preferably,the fork 14 is constructed as a composite of a plurality of sheets of acarbon fiber material within an epoxy resin matrix and incorporates avibration damping member comprised of an elastomeric material.Preferably the damping member comprises a thermoplastic elastomer, andmore preferably a viscoelastomeric material, as is described in greaterdetail below.

A steer tube 42 of the front fork assembly 14 extends through the frame12 of the bicycle 10 and supports the handlebar assembly 18 (FIG. 1) atits upper end. A pair of fork legs 44, 46 extend downward from the steertube 42 on opposing sides of the front wheel 16. The fork legs 44, 46are interconnected at an upper end 48, which is also connected to thesteer tube 42. An intermediate portion 56 of the fork legs 44, 46connects the upper portion 48 to the lower portion 52. Thus, each forkleg 44, 46 is a generally rigid member that defines a substantiallyconstant length. That is, preferably, the fork assembly 14 isconstructed such that relative movement between the front wheel 16 andthe bicycle frame 12 is substantially prevented. Such a construction iscommonly referred to as an unsuspended, or rigid, fork assembly.Furthermore, desirably, the fork legs 44, 46 and the steer tube 42 areof a one-piece construction.

A drop out 50 is secured to a lower end 52 of each fork leg 44, 46. Thedrop outs 50 are sized and shaped to receive an axle portion of a hub 54of the front wheel 16. Desirably, the drop outs 50 are constructed of ametal, such as aluminum or steel, and are secured to the fork legs 44,46 by a bonding process. However, other suitable arrangements to connectthe front wheel 16 to the fork assembly 14 may also be used.

With reference to FIGS. 1 and 2, desirably, the fork legs 44, 46 arearranged such that the hub 54 is supported on a forward side of an axisA defined by the steer tube 42. This is commonly referred to as the“rake” of the fork 14. Such an arrangement provides more stability tothe handling characteristics of the bicycle 10, as is well known in theart.

In the illustrated embodiment, the upper portion 48 of the fork legs 44,46 are substantially aligned with the axis A of the steer tube 42. Theintermediate portions 56 of the fork legs 44, 46 curve in a forwarddirection in the such that the lower ends 52 and drop outs 50 arepositioned forward of the axis of the bicycle 10. However, in otherarrangements, the fork legs 44, 46 may be substantially straight andmeet the steer tube 42 at an angle such that the hub 54 of the frontwheel 16 is positioned forward of the axis A.

With reference to FIG. 3, the intermediate portions 56 of the fork legs44, 46 are each curved inwardly in a lateral direction (i.e., toward oneanother) such that a distance therebetween is narrower than a distancebetween the upper portions 48 of the fork legs 44, 46. The lower ends 52of the fork 14 extend in an outward direction (i.e., away from oneanother) such that the distance therebetween is greater than thedistance between the intermediate portions 56. Such an arrangementdefines a generally hourglass-shaped space between the fork legs 44 and46, which conforms to the cross-sectional shape of the front wheel 16 toimprove the aerodynamics and vertical compliance of the fork assembly14.

As described above, each of the fork legs 44, 46 desirably define acavity in which a damping member 60 is positioned. Preferably, thedamping member 60 is located within the intermediate portion 56 of eachfork leg 44, 46 and, preferably, within the curve of the intermediateportion 56. Desirably, the damping member is substantially triangular inshape in a side elevational view. Such an arrangement advantageouslymaximizes the contact area between the damping member 60 and the forkleg 44, 46 within the space available, which enhances vibration damping,while preserving the strength and stiffness of the fork 14, whichimproves handling.

Furthermore, desirably the damping member 60 is substantially solid and,preferably, is completely solid. Such an arrangement advantageouslyprovides consistent, uniform vibration damping performance of thedamping member 60. In addition, desirably, the cross-sectional area ofthe damping member 60 is great enough to effectively dampen vibrationsfrom reaching the rider of the bicycle 10. In the context of a bicyclefront fork assembly 14, preferably the cross-sectional area of thelargest portion of the damping member 60 is about 60 mm² and, morepreferably, about 120 mm². However, other cross-sectional dimensions maybe desirable to provide a different level of vibration damping or forother applications.

With reference to FIGS. 4-6, the left fork leg 46 is shown in severalsectional views. The sectional views, and associated description of thefork leg 46, are described with reference to a coordinate system whereina vertical, longitudinal plane extends along the length of the bicycle10 and is substantially aligned with a plane defined by the frame 12 andwheels 16, 20. A vertical, lateral plane is substantially normal to thelongitudinal plane and a horizontal plane is substantially normal toboth the longitudinal and lateral planes.

FIG. 4 is a cross-sectional view of the fork leg 46 taken along ahorizontal plane and intersecting the damping member 60. FIG. 5 is apartial cross-sectional view of the fork leg 46 taken along a vertical,longitudinal plane and intersecting the damping member 60. FIG. 6 is apartial cross-sectional view of the fork leg 46 taken along a vertical,lateral plane and aligned with a front surface of the damping member 60.

As illustrated, desirably, the fork leg 46 is of a thin wall, hollowconstruction to reduce weight. Preferably, the fork leg 46 is comprisedof an outer wall portion 62, which defines an outer surface of the forkleg 46 and an internal wall portion 64, which defines a cavity 66, forreceiving the damping member 60. Thus, the outer wall portion 62 definesfront, rear, left-side and right-side wall portions of the fork leg 46.

Desirably, the outer and internal wall portions 62, 64 are continuouswith one another. As described above, desirably, the cavity 66 issubstantially triangular in shape and passes completely through the forkleg 46 in a lateral direction. Accordingly, the internal wall portion 64is substantially parallel to an axis of rotation AR of the front wheel16 (FIG. 3). Such an arrangement permits the fork leg 46 to maintainstrength in a longitudinal direction (i.e., the direction in which loadsare primarily imparted on the wheel 16), while incorporating the dampingmember 60. However, in other arrangements, the cavity 66 may pass onlypartially through the fork leg 46 and may be fully or partially closedon one, or both, sides.

With reference to FIG. 4, a central portion 68 of the damping member 60has a reduced thickness in a longitudinal direction such that a forwardand rearward surface of the central portion 68 conforms with the curvedforward and rearward portions of the wall 64 of the fork leg 46, whichdefines the cavity 66. That is, preferably, a width of the cavity 66 isreduced in a central portion thereof. Such an arrangement assists inretaining the damping member 60 within the cavity 66 and allowssubstantially complete contact between the wall 64 and the outerperimeter of the damping member 60. Desirably, the cross-section of thedamping member 60 is substantially consistent throughout its length.That is, the reduced thickness of the central portion 68 preferablyextends substantially the entire length of the damping member 60. Suchan arrangement advantageously assists in retaining the damping member 60within the cavity 66 due to the outer portions of the damping member 60being larger than the central portion of the cavity 60.

With reference to FIGS. 5 and 6, desirably, the damping member 60 iscurved along its length to conform with both the forward and lateralcurve of the fork leg 46, as described above. However, with reference toFIG. 6, an outer surface 72 of the damping member 60 (i.e., the surfaceopposite the wheel 16 in FIG. 3) is substantially linear in a verticaldirection. Such an arrangement enhances visibility of the damping member60.

Although not shown in detail, desirably, the right fork leg 44 issubstantially a mirror image of the left fork leg 46. However, as willbe readily appreciated by one of skill in the art, in other aspects thedamping member 60 of the right fork leg 44 is substantially identical tothat described above.

When constructed substantially as described above, the preferred forkassembly 14 inhibits vibrations from passing through the fork legs 44,46. Thus, vibrations originating at the lower end 52 of the fork legs44, 46 (i.e., at the front wheel 16) are inhibited from passing to theupper ends 48 and steer tube 42 of the fork 14 and, thus, the handlebar18 of the bicycle 10. Such an arrangement improves the comfort of therider and reduces fatigue during long rides.

Preferably, the entire fork assembly 14, with the exception of thedamping members 60, is constructed in a manner conventional forcomposite bicycle forks. However, the fork assembly 14 may beconstructed by any other suitable method. Desirably, the damping members60 are sized slightly larger than the cavities 66 and are retainedwithin the cavities 66 by contact friction therebetween. Preferably, thedamping members 60 are sized such that they may be assembled into thefork 14 by hand. However, the damping members 60 may also be press fitinto the cavities 66 using the assistance of a machine, such as a press,for instance.

Although the above-described process is preferred, the damping members60 may be secured within the cavities 66 by other means as well. Forexample, an adhesive may be used to create a chemical bond between thecontact surfaces of the damping member 60 and the wall 64 defining thecavity 66. In other arrangements, the damping member 60 may be assembledduring manufacturing of the fork assembly 14, such as by co-molding, forexample.

Of course, the foregoing description is that of certain features,aspects and advantages of the present invention to which various changesand modifications may be made without departing from the spirit andscope of the present invention. Moreover, a front fork assembly may notfeature all objects and advantages discussed above in order to usecertain features, aspects and advantages of the present invention. Thus,for example, those skilled in the art will recognize that the inventionmay be embodied or carried out in a manner that achieves or optimizesone advantage or a group of advantages as taught herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein. The present invention, therefore, should only bedefined by the appended claims.

1. A bicycle, comprising: a main frame portion; a wheel; a substantiallyrigid wheel support coupled to said main frame portion at a first endand supporting said wheel at a second end, an outer wall of said wheelsupport defining an opening to a cavity; and a damping member positionedwithin said cavity, wherein said damping member dampens vibrationsintroduced to said wheel support by said wheel.
 2. The bicycle of claim1, wherein said wheel is a front wheel of said bicycle and said wheelsupport is a front fork.
 3. The bicycle of claim 1, wherein said dampingmember is a solid piece of a elastomeric material.
 4. The bicycle ofclaim 3, wherein said damping member occupies substantially the entirevolume of the cavity.
 5. The bicycle of claim 1, wherein said cavityextends through said wheel support in a direction substantially parallelto an axis of rotation of said wheel.
 6. The bicycle of claim 5, whereinsaid cavity extends entirely through said wheel support.
 7. The bicycleof claim 1, wherein said wheel support comprises an internal wall thatdefines said cavity.
 8. The bicycle of claim 7, wherein said internalwall is formed continuously with said outer wall.
 9. The bicycle ofclaim 1, wherein said cavity is generally triangular in shape from aside view of said bicycle.
 10. The bicycle of claim 1, wherein saidcavity is located in an intermediate portion of said wheel supportbetween said first and second ends.